Absence of sum frequency generation in support of orthorhombic symmetry of α-chitin

Yu Ogawa, Christopher M. Lee, Yoshiharu Nishiyama, Seong H. Kim

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

The native polymorphic structures of chitin, namely α- and β-chitin, were studied with X-ray diffraction (XRD), infrared and Raman spectroscopies, and sum-frequency generation (SFG) vibrational spectroscopy. The currently proposed model of α-chitin crystal based on X-ray and electron diffraction study has an antiparallel chain arrangement imposed by the orthorhombic symmetry in contrast to parallel chain arrangements in β-chitin and native cellulose; however, the natural occurrence of antiparallel chain arrangement for α-chitin is controversial to widely accepted biosynthetic mechanisms for structural polysaccharides such as chitin and cellulose, where chains are successively polymerized and crystallized in a unidirectional way. We compared the SFG signals among samples with similar crystallinity, morphology, and textures but differing in allomorphs. The SFG signal from α-chitin was ∼40-fold weaker compared to β-chitin having a similar lateral dimension. The strong SFG signals arising from β-chitin can be explained by a net polar ordering of parallel packed chains. These results strongly supports the antiparallel chain orientation and high symmetry (orthorhombic) of α-chitin suggested by diffraction analysis.

Original languageEnglish (US)
Pages (from-to)7025-7031
Number of pages7
JournalMacromolecules
Volume49
Issue number18
DOIs
StatePublished - Sep 27 2016

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Chitin
Cellulose
X ray diffraction
Vibrational spectroscopy
Polysaccharides
Electron diffraction
Raman spectroscopy
Infrared spectroscopy
Textures
Diffraction

All Science Journal Classification (ASJC) codes

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

Cite this

Ogawa, Yu ; Lee, Christopher M. ; Nishiyama, Yoshiharu ; Kim, Seong H. / Absence of sum frequency generation in support of orthorhombic symmetry of α-chitin. In: Macromolecules. 2016 ; Vol. 49, No. 18. pp. 7025-7031.
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Absence of sum frequency generation in support of orthorhombic symmetry of α-chitin. / Ogawa, Yu; Lee, Christopher M.; Nishiyama, Yoshiharu; Kim, Seong H.

In: Macromolecules, Vol. 49, No. 18, 27.09.2016, p. 7025-7031.

Research output: Contribution to journalArticle

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